With single or multi-cam systems of this type for flat-bed knitting machines, as disclosed, for example, in German laid open application 31 38 981, the transfer cam parts are provided with a so-called triple lobe cam profile, this means, as well as having the one common transfer lobe, it has two pretensioning lobes of which one preceeds in one direction and the other in the other direction. This means, that the needles in each direction must allow the appropiate trailing pretensioning lobe, which when trailing does not operate, to also pass through. The design of the transfer cam parts in the form of a triple lobe cam requires a relatively wide cam and correspondingly, a relatively wide carriage as well, which results in a certain loss of efficiency and an unnecessary strain on the thread material.
To reduce the cam and carriage width of such types of single or multi-cam systems as this, it is disclosed in German laid open application No. 32 11 515 to equip the transfer cam parts with a so-called twin lobe cam profile only, and to move it in such a manner, that the leading lobe is always the higher pretensioning lobe and the trailing lobe is always the lower transfer lobe. However, one has to tolerate the fact the additional drive and/or switching devices must be provided for moving the transfer cam part in question.